from collections import ChainMap

a = {'a': 'A', 'c': 'C'}
b = {'b': 'B', 'c': 'D'}
c = {'c': 'E'}

m1 = ChainMap(a, b)
m2 = m1.new_child(c)

print('m1 : ', m1)
print('m2 : ', m2)
